Cell Envelope Homeostasis in Bacillus subtilis

项目概要 细菌被细胞膜包围，这对于生长、完整性和发病机制至关重要。的 包膜和构建它的生物发生途径也是我们许多最有效抗生素的目标 和疫苗疗法。由于细胞被膜生物发生已成为一个如此成功的目标，因此它已成为 半个多世纪以来一直活跃的研究领域。大多数负责合成和重塑的基因 不同表面聚合物的种类已被鉴定并表征了它们的生化活性。然而， 我们对这些不同组装途径如何相互调节和协调的理解 期间增长仍然有限。 该提案重点关注与细菌如何协调包膜组装相关的两个悬而未决的问题， 两者都主要关注细胞壁肽聚糖（PG）。细胞生长需要PG合成，但也需要 细胞壁水解酶的活性，以允许 PG 网络扩张。这些潜在的裂解酶是如何产生的 对于所有细菌来说，与生长的调节和协调仍然是一个悬而未决的问题。前两个目标 该提案重点关注模型革兰氏阳性细菌枯草芽孢杆菌如何调节两种功能 多余的细胞壁水解酶及其如何与细胞壁合成和包膜协调其活性 扩张。第三个目标侧重于细胞如何感知和响应细胞壁生物发生的扰动。的 二十多年前，σM 信号通路被认为是一种应激反应通路，由 环境压力，包括针对抗生素的细胞壁。该途径在中间水平活跃 在细胞包膜稳态不受干扰的生长和功能期间，监测包膜组装和 通过 PG 生物发生途径调节通量。该通路感知什么以及它如何转换它 跨膜信息仍然是神秘的。拟议研究的结果将阐明 包膜生物合成中的关键调控途径，并将为新疗法的开发提供信息 感染。该应用程序的具体目标是： 目标 1：阐明细胞如何感知和响应 PG 交联程度，以确保适当的扩增 细胞壁。 目标 2 研究生长过程中细胞壁水解与细胞壁合成如何协调。 目标 3：确定细胞如何感知和响应细胞包膜生物发生的扰动。

PROJECT SUMMARY Bacteria are surrounded by a cell envelope that is essential for growth, integrity, and pathogenesis. The envelope and the biogenesis pathways that build it are also the target of many of our most effective antibiotic and vaccine therapies. Because cell envelope biogenesis has been such a successful target, it has been an active area of research for over half a century. Most of the genes responsible for the synthesis and remodeling of the different surface polymers have been identified and their biochemical activities characterized. However, our understanding of how these different assembly pathways are regulated and coordinated with each other during growth remains limited. This proposal focuses on two outstanding questions related to how bacteria coordinate envelope assembly, both principally focused on the cell wall peptidoglycan (PG). Cell growth requires PG synthesis but also the activity of cell wall hydrolases to allow expansion of the PG meshwork. How these potentially lytic enzymes are regulated and coordinated with growth remains an unanswered question in all bacteria. The first two aims of this proposal focus on how the model gram-positive bacterium Bacillus subtilis regulates two functionally redundant cell wall hydrolases and how it coordinates their activities with cell wall synthesis and envelope expansion. The third aim focuses on how cells sense and respond to perturbations to cell wall biogenesis. The σM-signaling pathway was identified over two decades ago as a stress-response pathway that is induced upon environmental stresses, including cell wall targeting antibiotics. This pathway is active at intermediate levels during unperturbed growth and functions in cell envelope homeostasis, monitoring envelope assembly and adjusting flux through the PG biogenesis pathway. What this pathway senses and how it transduces this information across the membrane have remained mysterious. The results of the proposed studies will elucidate critical regulatory pathways in envelope biogenesis and will inform the development of new treatments for infections. The Specific Aims of this application are: Aim 1: Elucidate how cells sense and respond to the extent of PG crosslinking to ensure proper expansion of the cell wall. Aim 2 Investigate how cell wall hydrolysis is coordinated with cell wall synthesis during growth. Aim 3: Determine how cells sense and respond to perturbations to cell envelope biogenesis.